The invention set forth in this specification pertains to a new and improved method and apparatus for treating a fluid by electron emission. It is commonplace to refer to such treatment as treatment by corona discharge. The invention is primarily directed toward a method and apparatus for the production of ozone but is of such a character that it is considered to be applicable to the treatment of a variety of different fluids in connection with the production of a number of different products.
It is well known to treat a fluid such as air, oxygen enriched air or pure oxygen by electron emission or corona discharge by passing the fluid through the space between a dielectric layer located on the surface of a first electrode and a second electrode while an appropriate circuit is used in order to cause electron emission or corona discharge within the space. As an apparatus or cell of this type is operated normally a significant amount of heat is developed and this heat causes expansion of the materials present within an apparatus or cell including the parts indicated in the preceding. Since the heat buildup within such an apparatus or cell is considered detrimental to the production of certain compounds such as ozone it is known to cool the apparatus or cell used.
Such cooling can, of course, be accomplished in a number of ways. Most commonly it has been established by circulating cooling fluids past surfaces within a cell or apparatus as noted which are remote from the space where the electron emission or corona discharge occurs. While such cooling as conventionally carried out is desirable in improving the efficiency of cell performance it does not serve to optimize cell efficiency to a desired extent.
This is related to the fact that a cell for fluid treatment by electron emission or corona discharge as used with an electrical circuit connected to the electrodes in such a cell for the purpose of causing electron emission or corona discharge in effect acts as a component of such an electrical circuit. As the cell or apparatus is operated by such a circuit it can be considered as a capacitance connected into such a circuit. It can also be considered as a network including several capacitors, a resistor and a bidirectional zener diode connected into such a circuit as a part of such a circuit. When there is a variation in the electrical characteristics of such a cell such a variation will affect the operation of the connected "driving" circuit. This may alter the frequency of the pulses supplied to the cell and/or wave form of the pulses supplied to the apparatus or cell. Normally any such variation in the operation of the circuit used to operate the cell will detrimentally affect the efficiency. This is particularly the case in connection with circuits such as are shown and described in the aforenoted U.S. Pat. No. 4,051,043.
It is considered obvious any heat buildup within the interior of a cell or apparatus as noted will tend to cause some dimensional changes within the interior of such a cell or apparatus. Such dimensional changes will result from heat caused expansion. Even comparatively minor dimensional changes of this type will affect the capacitance characteristics of the cell or apparatus and to a degree tend to affect other related electrical characteristics growing out of the manner in which such a cell or apparatus operates so as to in effect form a part of the power supply circuit.
Such changes in electrical characteristics are of course minimized by the conventional use of cooling fluids as indicated in the preceding discussion. Even so it is considered that it is effectively impossible to utilize such cooling fluids so as to stabilize the electrical characteristics of an apparatus or cell for fluid treatment by electron emission or corona discharge to a desired extent so as to prevent changes in cell dimensions from changing cell electrical characteristics to the extent necessary to avoid such changes causing an interference in the desired manner of supplying power to such a cell or apparatus.
Further, it is considered that even with known types of cooling the performance of a cell or apparatus as noted is unnecessarily detrimentally affected because of another factor which is related to mechanical stability. In a cell or apparatus as noted the dielectric layer is a critical component as far as cell operation is concerned. A great deal of research and development work has gone into the development of dielectric layers for use in apparatus for fluid treatment by electron emission which are capable of being used over a prolonged period without dielectric breakdown. A particularly desirable type of dielectric for use in such cells or apparatus is set forth in the aforenoted application Ser. No. 652,633 now U.S. Pat. No. 4,051,043.
A dielectric as set forth in this patent is, particularly after use, a rather brittle, somewhat fragile type structure which is apt to be damaged as a result of any physical deformation. Other known dielectrics are normally of a similar character. It is not considered that the present cooling techniques as are employed in connection with cells or apparatus as noted are adequate to minimize heat caused dielectric deformation which will tend to shorten the useful life of the dielectric in an apparatus or cell as noted.